From d0157d93d24c8c7f1a86289efe29e203d98bb072 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Mon, 5 Nov 2012 09:01:39 +0000
Subject: Factor pushMatchingRanges, improve comments/tests 1. Factor out
 `pushMatchingRanges`:    This then allows us to ... 2. Add unit tests for
 `pushMatchingRanges`    In effect, these tests verify where matches are
 highlighted in suggestions. 3. Added Utils.zip.  This helps simplify
 `pushMatchingRanges` unit tests. 4. Improve comments.

---
 background_scripts/completion.coffee | 42 +++++++++++++++++++++++++-----------
 1 file changed, 30 insertions(+), 12 deletions(-)

(limited to 'background_scripts/completion.coffee')

diff --git a/background_scripts/completion.coffee b/background_scripts/completion.coffee
index c8a06b27..ab24377a 100644
--- a/background_scripts/completion.coffee
+++ b/background_scripts/completion.coffee
@@ -46,19 +46,32 @@ class Suggestion
     url = url.substring(url, url.length - 1) if url[url.length - 1] == "/"
     url
 
+  # Push the ranges within `string` which match `term` onto `ranges`.
+  pushMatchingRanges: (string,term,ranges) ->
+    textPosition = 0
+    # Split `string` into a (flat) list of pairs:
+    #   - splits[i%2] is unmatched text
+    #   - splits[(i%2)+1] is the following matched text (matching `term`)
+    #     (except for the final element, for which there is no following matched text).
+    # Example:
+    #   - string = "Abacab"
+    #   - term = "a"
+    #   - splits = [ "", "A",    "b", "a",    "c", "a",    b" ]
+    #                UM   M       UM   M       UM   M      UM      (M=Matched, UM=Unmatched)
+    splits = string.split(RegexpCache.get(term, "(", ")"))
+    for index in [0..splits.length-2] by 2
+      unmatchedText = splits[index]
+      matchedText = splits[index+1]
+      # Add the indices spanning `matchedText` to `ranges`.
+      textPosition += unmatchedText.length
+      ranges.push([textPosition, textPosition + matchedText.length])
+      textPosition += matchedText.length
+
   # Wraps each occurence of the query terms in the given string in a <span>.
   highlightTerms: (string) ->
     ranges = []
     for term in @queryTerms
-      textPosition = 0
-      splits = string.split(RegexpCache.get(term, "(", ")")).reverse()
-      while 0 < splits.length
-        unmatchedText = splits.pop()
-        textPosition += unmatchedText.length
-        matchedText = if 0 < splits.length then splits.pop() else null
-        if matchedText
-          ranges.push([textPosition, textPosition + matchedText.length])
-          textPosition += matchedText.length
+      @pushMatchingRanges string, term, ranges
 
     return string if ranges.length == 0
 
@@ -314,9 +327,14 @@ RegexpCache =
 
   clear: -> @cache = {}
 
-  # Get rexexp for string from cache, creating the regexp if necessary.
-  # Regexp meta-characters in string are escaped.
-  # Regexp is wrapped in prefix/suffix, which may contain meta-characters.
+  # Get rexexp for `string` from cache, creating it if necessary.
+  # Regexp meta-characters in `string` are escaped.
+  # Regexp is wrapped in `prefix`/`suffix`, which may contain meta-characters (these are not escaped).
+  # With their default values, `prefix` and `suffix` have no effect.
+  # Example:
+  #   - string="go", prefix="\b", suffix=""
+  #   - this returns regexp matching "google", but not "agog" (the "go" must occur at the start of a word)
+  # TODO: `prefix` and `suffix` might be useful in richer word-relevancy scoring.
   get: (string, prefix="", suffix="") ->
     @init() unless @initialized
     regexpString = string.replace(@escapeRegExp, "\\$&")
-- 
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